How can I find out if there's a tower near my house?

You need to visit your nearest BSNL Customer Service Centre and they will check your address.

Can I use a EVDO device to access CDMA 1x network?

Since EVDO devices offers backward compatibility, you can access a CDMA 1x network with EVDO device.

Can I access EVDO Network with CDMA 1x device?

No, you can't.

Does EVDO device use a R-UIM / SIM card?

Yes.

Where can I buy EVDO device?

You can buy the EVDO device at your local BSNL Customer Service Centre or through market.

Can I use this device with Windows Vista ?

Yes you can.